Organic EL panel, display device using same, and method for producing organic EL panel

ABSTRACT

To increase light-extraction efficiency and simplify manufacturing process. An organic EL panel includes: first electrode reflecting incident light; second electrode transmitting incident light therethrough; organic light-emitting layer emitting light of corresponding color among R, G, and B colors; first functional layer including charge injection/transport layer and at least one other layer, and disposed between the first electrode and the light-emitting layer; and second functional layer disposed between the second electrode and the light-emitting layer. The charge injection/transport layers of R and G colors are equal in film thickness, and differ in film thickness from the charge injection/transport layer of the B color, the at least one other layers of R, G, and B colors are equal in film thickness, the second functional layers of R, G, and B colors are equal in film thickness, and the light-emitting layers of R, G, and B colors differ in film thickness.

TECHNICAL FIELD

The present invention relates to an organic EL panel that relies onelectroluminescence phenomenon of organic materials, a display devicewith the organic EL panel, and a method of manufacturing the organic ELpanel. The present invention particularly relates to optical design forincreasing light-extraction efficiency of each of R (Red), G (Green),and B (Blue) colors.

BACKGROUND ART

In recent years, there has been proposed adoption of organic EL (ElectroLuminescence) panels that rely on electroluminescence phenomenon oforganic materials as display panels for display devices such as digitaltelevisions. A matrix of respective organic EL elements of the R, G, andB colors is arranged in a substrate of an organic EL panel.

It is important to increase light-extraction efficiency of therespective organic EL elements of the R, G, and B colors, from thestandpoint of reducing power consumption, increasing service life of theorganic EL panels, and the like. To this end, there has been proposed anumber of arts for increasing light-extraction efficiency owing tocreativity of optical design of the organic EL elements (see PatentLiteratures 1 to 7). For example, Patent Literature 7 discloses thatrespective light-emitting elements of the R, G, and B colors are eachconstituted from a lower electrode (mirror), a transparent conductivelayer, a hole transport layer, a light-emitting layer, an electrontransport layer, and an upper electrode (half mirror) that are layered,and the optical distance between the mirror and the half mirror isadjusted in order to exhibit a local maximum of light-extractionefficiency of each of the R, G, and B colors (paragraph 0012). Accordingto Patent Literature 7, the optical distance is adjusted by adjustingthe film thickness of the transparent conductive layer for each of theR, G, and B colors.

CITATION LIST Patent Literature

-   [Patent Literature 1] Japanese Patent Application Publication No.    2006-156344-   [Patent Literature 2] Japanese Patent Application Publication No.    2005-317255-   [Patent Literature 3] Japanese Patent Application Publication No.    2005-322435-   [Patent Literature 4] Japanese Patent Application Publication No.    2005-100946-   [Patent Literature 5] Japanese Patent Application Publication No.    2008-41925-   [Patent Literature 6] Japanese Patent Application Publication No.    2006-179780-   [Patent Literature 7] Japanese Patent Application Publication No.    2005-116516

SUMMARY OF INVENTION Technical Problem

According to the above conventional art, however, the film thickness ofthe transparent conductive layer needs to be adjusted for each of the R,G, and B colors, and this complicates the manufacturing process.

In view of the above problem, the present invention aims to provide anorganic EL panel, a display device with use of the organic EL panel, anda method of manufacturing the organic EL panel according to whichlight-extraction efficiency is increased due to light interferencephenomenon, and the manufacturing process is simplified compared withconventional arts.

Solution to Problem

One aspect of the present invention provides an organic EL panelcomprising: a first electrode of each of R (red), G (green), and B(blue) colors that reflects incident light; a second electrode thatfaces the first electrode of each of the R, G, and B colors, andtransmits incident light therethrough; an organic light-emitting layerof each of the R, G, and B colors that is disposed between the firstelectrode of a corresponding color and the second electrode, and emitslight of a corresponding color due to voltage application between thefirst electrode of the corresponding color and the second electrode; afirst functional layer of each of the R, G, and B colors that includes acharge injection/transport layer and at least one other layer, and isdisposed between the first electrode of a corresponding color and theorganic light-emitting layer of a corresponding color; and a secondfunctional layer of each of the R, G, and B colors that is disposedbetween the second electrode and the organic light-emitting layer of acorresponding color, wherein a first portion of light of each of the R,G, and B colors emitted from the organic light-emitting layer of acorresponding color travels through the first functional layer of acorresponding color towards the first electrode of a correspondingcolor, strikes and is reflected by the first electrode of thecorresponding color, and then is emitted externally after passingthrough the first functional layer of the corresponding color, theorganic light-emitting layer of the corresponding color, the secondfunctional layer of a corresponding color and the second electrode, asecond portion of the light of each of the R, G, and B colors travelsthrough the second functional layer of the corresponding color towardsthe second electrode instead of towards the first electrode of thecorresponding color, and is emitted externally after passing through thesecond electrode, the respective charge injection/transport layers ofthe R and G colors are equal in film thickness to each other, and differin film thickness from the charge injection/transport layer of the Bcolor, the respective at least one other layers of the R, G, and Bcolors are equal in film thickness to one another, the respective secondfunctional layers of the R, G, and B colors are equal in film thicknessto one another, and the respective organic light-emitting layers of theR, G, and B colors differ in film thickness from one another.

Advantageous Effects of Invention

Generally, the organic light-emitting layer needs to be formedseparately for each of the R, G, and B colors irrespective of whetherhaving the same film thickness among the R, G, and B colors, because ofbeing formed from a different material for each of the R, G, and Bcolors. Compared with this, the first functional layer and the secondfunctional layer are each formed from the same material among the R, G,and B colors. Accordingly, if differing in film thickness among the R,G, and B colors, the first functional layer and the second functionallayer each need to be formed separately for each of the R, G, and Bcolors. Otherwise, the first functional layer and the second functionallayer each do not need to be formed separately for each of the R, G, andB colors. In order to make a layer to differ in film thickness for eachof the R, G, and B colors, a printing method such as the inkjet methodfacilitates film formation for each of the R, G, and B colors. Notethat, depending on the type of layer, there is a case where the printingmethod is unavailable for film formation, a case where though theprinting method is available for film formation, other film formationmethod is more appropriate for exhibiting desired characteristics, orthe like. Accordingly, film formation cannot be always made by a filmformation method according to which film formation for each of the R, G,and B colors is easily made.

According to the organic EL panel that is the one aspect of the presentinvention, the organic light-emitting layer and the holeinjection/transport layer are each formed separately to have a filmthickness for each of the R, G, and B colors. In this way, filmformation is made separately to obtain a film thickness for each of theR, G, and B colors, and accordingly it is possible to take advantage oflight interference phenomenon. Also, since the organic light-emittinglayer originally needs to be formed separately to have a film thicknessfor each of the R, G, and B colors, there is no increase in the numberof manufacturing processes due to separate formation of the organiclight-emitting layer to have a film thickness for each of the R, G, andB colors. The hole injection/transport layer is appropriate forformation by the printing method, and accordingly is easily formedseparately to have a film thickness for each of the R, G, and B colors.As a result, it is possible to increase light-extraction efficiencytaking advantage of light interference phenomenon, and simplify themanufacturing process compared with conventional arts.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional diagram schematically showing the pixelstructure of an organic EL panel according to an embodiment of thepresent invention.

FIG. 2 shows an example of a cavity structure in a blue organic ELelement.

FIG. 3 shows the transmission spectrum of each of respective colorfilters (CFs) of the R, G, and B colors used in simulations.

FIG. 4A to FIG. 4D show variation of light-extraction efficiency whenvarying the film thickness of a first functional layer, FIG. 4A showsthe case where no CF is used in Example 1, FIG. 4B shows the case whereCFs are used in Example 1, FIG. 4C shows the case where no CF is used inComparative example 1, and FIG. 4D shows the case where CFs are used inComparative example 1.

FIG. 5A to FIG. 5D each show variation of light-extraction efficiencywhen varying the film thickness of a layer constituting an organic ELelement, FIG. 5A and FIG. 5B show variation of light-extractionefficiency when varying the film thickness of a hole transport layer, inthe case where no CF is used and the case where CFs are used,respectively, and FIG. 5C and FIG. 5D show variation of light-extractionefficiency when varying the film thickness of an organic light-emittinglayer, in the case where no CF is used and the case where CFs are used,respectively.

FIG. 6A and FIG. 6B show light-extraction efficiency and so on when eachlayer constituting an organic EL element is set to have an optimal filmthickness in Example 1 and Comparative example 1, respectively.

FIG. 7 show allowable ranges.

FIG. 8A to FIG. 8C each show the minimum value, the average value, andthe maximum value of the film thickness of each layer constituting theorganic EL element in Example 1, with respect to the R, G, and B colors,respectively.

FIG. 9 is a functional block showing an organic display device accordingto the embodiment of the present invention.

FIG. 10 is an exemplary external diagram showing the organic displaydevice according to the embodiment of the present invention.

FIG. 11A to FIG. 11D show a method of manufacturing the organic EL panelaccording to the embodiment of the present invention.

FIG. 12A to FIG. 12C show the method of manufacturing the organic ELpanel according to the embodiment of the present invention.

DESCRIPTION OF EMBODIMENT

[Process by which Aspect of the Present Invention was Achieved]

Before concretely describing one aspect of the present invention, thefollowing describes the process by which the aspect of the presentinvention was achieved.

The present inventors have been made researches and developments on anorganic EL panel. This organic EL panel is constituted from a firstelectrode, a first functional layer, an organic light-emitting layer, asecond functional layer, and a second electrode that are layered, andhas specifications in which the first electrode reflects light and thesecond electrode transmits the light therethrough. According to suchspecifications, a distance between the first electrode and the organiclight-emitting layer, that is, the film thickness of the firstfunctional layer strongly influences light interference phenomenon. Forthis reason, it is considered that, in order to increaselight-extraction efficiency for each of the R, G, and B colors, the filmthickness of the first functional layer should be appropriately adjustedfor each of the R, G, and B colors.

Also, the researches made by the present inventors proved that theorganic EL panel having the above specifications has the structure inwhich the light-extraction efficiency varies also in accordance withvariation of the film thickness of the organic light-emitting layer.FIG. 5A to FIG. 5D show the result of the researches. FIG. 5A and FIG.5B show variation of light-extraction efficiency when varying the filmthickness of a hole transport layer included in the first functionallayer, in the case where no CF is used and the case where CFs are used,respectively. FIG. 5C and FIG. 5D show variation of light-extractionefficiency when varying the film thickness of an organic light-emittinglayer, in the case where no CF is used and the case where CFs are used,respectively. According to this proof, it is clear that thelight-extraction efficiency varies not only when the film thickness ofthe first functional layer is varied but also when the film thickness ofthe organic light-emitting layer is varied.

By the way, in general, the organic light-emitting layer needs to beformed separately for each of the R, G, and B colors irrespective ofwhether having the same film thickness among the R, G, and B colors,because of being formed from a different material for each of the R, G,and B colors. Compared with this, the first functional layer and thesecond functional layer are each formed from the same material among theR, G, and B colors. Accordingly, if differing in film thickness amongthe R, G, and B colors, the first functional layer and the secondfunctional layer each need to be formed separately for each of the R, G,and B colors. Otherwise, the first functional layer and the secondfunctional layer each do not need to be formed separately for each ofthe R, G, and B colors. In order to make a layer to differ in filmthickness for each of the R, G, and B colors, a printing method such asthe inkjet method facilitates film formation for each of the R, G, and Bcolors. Note that, depending on the type of layer, there is a case wherethe printing method is unavailable for film formation, a case wherethough the printing method is available for film formation, other filmformation method is more appropriate for exhibiting desiredcharacteristics, or the like. Accordingly, it is not always appropriateto make film formation by the printing method.

In view of the results shown in FIG. 5A to FIG. 5D and the abovecircumstances, the present inventors considered whether it is possibleto achieve the increase in light-extraction efficiency and thesimplification of the manufacturing process, only by film thicknessadjustment on the organic light-emitting layer for each of the R, G, andB colors. However, the variation of light-extraction efficiency withrespect to the variation of the film thickness of the organiclight-emitting layer is smaller than the variation of light-extractionefficiency with respect to the variation of the film thickness of thefirst functional layer (see respective ranges h1 and h2 shown in FIG. 5Band FIG. 5D). This proves that it is impossible to sufficiently increasethe light-extraction efficiency, especially the light-extractionefficiency of the B color, only by film thickness adjustment on theorganic light-emitting layer for each of the R, G, and B colors.

The one aspect of the present invention was achieved based on the newexpertise described above.

[Outline of Aspects of the Present Invention]

One aspect of the present invention provides an organic EL panelcomprising: a first electrode of each of R (red), G (green), and B(blue) colors that reflects incident light; a second electrode thatfaces the first electrode of each of the R, G, and B colors, andtransmits incident light therethrough; an organic light-emitting layerof each of the R, G, and B colors that is disposed between the firstelectrode of a corresponding color and the second electrode, and emitslight of a corresponding color due to voltage application between thefirst electrode of the corresponding color and the second electrode; afirst functional layer of each of the R, G, and B colors that includes acharge injection/transport layer and at least one other layer, and isdisposed between the first electrode of a corresponding color and theorganic light-emitting layer of a corresponding color; and a secondfunctional layer of each of the R, G, and B colors that is disposedbetween the second electrode and the organic light-emitting layer of acorresponding color, wherein a first portion of light of each of the R,G, and B colors emitted from the organic light-emitting layer of acorresponding color travels through the first functional layer of acorresponding color towards the first electrode of a correspondingcolor, strikes and is reflected by the first electrode of thecorresponding color, and then is emitted externally after passingthrough the first functional layer of the corresponding color, theorganic light-emitting layer of the corresponding color, the secondfunctional layer of a corresponding color and the second electrode, asecond portion of the light of each of the R, G, and B colors travelsthrough the second functional layer of the corresponding color towardsthe second electrode instead of towards the first electrode of thecorresponding color, and is emitted externally after passing through thesecond electrode, the respective charge injection/transport layers ofthe R and G colors are equal in film thickness to each other, and differin film thickness from the charge injection/transport layer of the Bcolor, the respective at least one other layers of the R, G, and Bcolors are equal in film thickness to one another, the respective secondfunctional layers of the R, G, and B colors are equal in film thicknessto one another, and the respective organic light-emitting layers of theR, G, and B colors differ in film thickness from one another.

According to the organic EL panel that is the one aspect of the presentinvention, the organic light-emitting layer and the holeinjection/transport layer are each formed separately to have a filmthickness for each of the R, G, and B colors. In this way, filmformation is made separately to obtain a film thickness for each of theR, G, and B colors, and accordingly it is possible to take advantage oflight interference phenomenon. Also, since the organic light-emittinglayer originally needs to be formed separately to have a film thicknessfor each of the R, G, and B colors, there is no increase in the numberof manufacturing processes due to separate formation of the organiclight-emitting layer to have a film thickness for each of the R, G, andB colors. The hole injection/transport layer is appropriate forformation by the printing method, and accordingly is easily formedseparately to have a film thickness for each of the R, G, and B colors.As a result, it is possible to increase light-extraction efficiencytaking advantage of light interference phenomenon, and simplify themanufacturing process compared with conventional arts.

Note that the “charge injection/transport layer” is a collective name ofa hole injection layer, a hole transport layer, a hole injection andtransport layer, an electron injection layer, an electron transportlayer, and an electron injection and transport layer.

Also, the organic EL panel may further comprise a color filter of eachof the R, G, and B colors for chromaticity correction that is disposedopposite the organic light-emitting layer of a corresponding color withthe second electrode being interposed therebetween, wherein the filmthickness of the organic light-emitting layer of each of the R, G, and Bcolors is adjusted so as to correspond to a local maximum oflight-extraction efficiency with respect to the light of thecorresponding color emitted externally through the color filter of thecorresponding color.

The researches made by the present inventors proved that when the filmthickness of each layer constituting an organic EL element is varied,both the light-extraction efficiency and the chromaticity vary, and thata chromaticity corresponding to a local maximum of light-extractionefficiency is not necessarily at the neighborhood of a targetchromaticity.

The more greatly a current chromaticity differs from the targetchromaticity, the more chromaticity correction needs to be made with useof a color filter (CF). As a result, there is a case where though achromaticity before chromaticity correction corresponds to a localmaximum of light-extraction efficiency, a chromaticity after thechromaticity correction does not correspond to a local maximum oflight-extraction efficiency. According to the one aspect of the presentinvention, the film thickness of the organic light-emitting layer is setso as to correspond to a local maximum of light-extraction efficiencywith respect to light after passing through a color filter. Therefore,it is possible to make the current chromaticity to approach to thetarget chromaticity and increase the light-extraction efficiency.

Also, a film thickness of the first functional layer of each of the R,G, and B colors may be adjusted so as to correspond to a second localmaximum of the light-extraction efficiency with respect to the light ofthe corresponding color emitted externally through the color filter ofthe corresponding color.

Variation of the film thickness of the first functional layer causescyclic variation of the light-extraction efficiency. As a result, alocal maximum of light-extraction efficiency cyclically appears. Here, alocal maximum that cyclically appears is referred to as the first localmaximum, the second local maximum, and the third local maximum, . . . ,in order of increasing corresponding film thickness of the firstfunctional layer. When the first functional layer has a too thin filmthickness, it is difficult to realize stable film formation. Accordingto the one aspect of the present invention, the first functional layerhas a film thickness such that the first functional layer is stablyformed.

Also, the first functional layer of each of the R, G, and B colors mayinclude, as the at least one other layer, a transparent conductivelayer.

While it is possible to form the transparent conductive layer by thephysical vapor deposition method, it is difficult to form thetransparent conductive layer by the printing method. According to theone aspect of the aspect of the present invention, the respectivetransparent conductive layers of the R, G, and B colors have the samefilm thickness. This simplifies the manufacturing process.

Also, the first functional layer of each of the R, G, and B colors mayinclude a layer formed by a printing method and a layer formed by aphysical vapor deposition method, the respective layers of the R and Gcolors formed by the printing method may be equal in film thickness toeach other, and differ in film thickness from the layer of the B colorformed by the printing method, and the respective layers of the R, G,and B colors formed by the physical vapor deposition method may be equalin film thickness to one another.

This simplifies the manufacturing process of the organic EL panel.

Also, the respective organic light-emitting layers of the R, G, and Bcolors may have a film thickness of 90 nm to 110 nm, a film thickness of72 nm to 88 nm, and a film thickness of 27 nm to 33 nm, respectively,the first functional layer of each of the R, G, and B colors mayinclude, as the at least one other layer, a transparent conductive layerformed on an anode that is the first electrode of the correspondingcolor, the first functional layer of each of the R, G, and B colors mayinclude, as the charge injection/transport layer, a hole injection layerformed on the transparent conductive layer and a hole transport layerformed on the hole injection layer, the respective transparentconductive layers of the R, G, and B colors each may have a filmthickness of 90 nm to 110 nm, the respective hole injection layers ofthe R, G, and B colors each may have a film thickness of 36 nm to 44 nm,and the respective hole transport layers of the R and G colors each mayhave a film thickness of 45 nm to 55 nm, and the hole transport layer ofthe B color has a film thickness of 18 nm to 22 nm.

Also, the first electrode of each of the R, G, and B colors may beformed from aluminum or alloy of aluminum, and the transparentconductive layer of each of the R, G, and B colors may be formed fromIZO (Indium Zinc Oxide).

Also, the respective second functional layers of the R, G, and B colorseach may have a film thickness of 27 nm to 33 nm.

Also, the second functional layer of each of the R, G, and B colors mayinclude an electron transport layer having a film thickness of 27 nm to33 nm.

Also, the organic light-emitting layer of each of the R, G, and B colorsmay contain an organic material, and may be formed by a printing method.

Also, the first functional layer of each of the R, G, and B colors mayinclude, as the at least one other layer, a transparent conductive layerformed on an anode that is the first electrode of the correspondingcolor, the first functional layer of each of the R, G, and B colors mayinclude, as the charge injection/transport layer, a hole injection layerformed on the transparent conductive layer and a hole transport layerformed on the hole injection layer, the transparent conductive layer ofeach of the R, G, and B colors and the hole injection layer of each ofthe R, G, and B colors may be formed by a physical vapor depositionmethod, and the hole transport layer of each of the R, G, and B colorsmay be formed by a printing method.

One aspect of the present invention provides a display device with useof the above organic EL panel.

One aspect of the present invention provides A method of manufacturingan organic EL panel, comprising: a first step of preparing a firstelectrode of each of R (red), G (green), and B (blue) colors thatreflects incident light; a second step of disposing a first functionallayer of each of the R, G, and B colors including a chargeinjection/transport layer and at least one other layer on the firstelectrode of a corresponding color; a third step of disposing an organiclight-emitting layer that emits light of each of the R, G, and B colorson the first functional layer of a corresponding color; a fourth step ofdisposing a second functional layer of each of the R, G, and B colors onthe organic light-emitting layer of a corresponding color; and a fifthstep of disposing a second electrode that transmits incident lighttherethrough on the respective second functional layers of the R, G, andB colors so as to face the respective first electrodes of the R, G, andB colors, wherein in the second step, the first functional layer isdisposed such that the respective charge injection/transport layers ofthe R and G colors are equal in film thickness to each other, and differin film thickness from the charge injection/transport layer of the Bcolor, and the respective at least one other layers of the R, G, and Bcolors are equal in film thickness to one another, in the third step,the organic light-emitting layer is disposed such that the respectiveorganic light-emitting layers of the R, G, and B colors differ in filmthickness from one another, and in the fourth step, the secondfunctional layer is disposed such that the respective second functionallayers of the R, G, and B colors are equal in film thickness to oneanother.

In the present Description, the expressions “have the same filmthickness”, “equal in film thickness”, and so on indicate not only thecase where respective layers of the R, G, and B colors have the samemeasured value of film thickness, but also the case where the respectivelayers of the R, G, and B colors each have a different measured value offilm thickness within a manufacturing error range of ±10%.

[Pixel Structure of Organic EL Panel]

FIG. 1 is a cross-sectional diagram schematically showing the pixelstructure of an organic EL panel according to an embodiment of thepresent invention.

The organic EL panel has R, G, and B pixels arranged regularly in amatrix of rows and columns. Each pixel is formed by an organic ELelement with use of an organic material.

The blue organic EL element includes a substrate 1, a reflectiveelectrode 2, a transparent conductive layer 3, a hole injection layer 4,a hole transport layer 5, an organic light-emitting layer 6 b, anelectron transport layer 7, a transparent electrode 8, a thin-filmpassivation layer 9, a resin passivation layer 10, a substrate 11, and aCF 13 b. Hereinafter, the transparent conductive layer 3, the holeinjection layer 4, and the hole transport layer 5 that are disposedbetween the reflective electrode 2 and the organic light-emitting layer6 b are also collectively referred to as “first functional layer”.Furthermore, the electron transport layer 7 that is disposed between theorganic light-emitting layer 6 b and the transparent electrode 8 is alsoreferred to as “second functional layer”.

The green organic EL element has the same structure as the blue organicEL element, except for an organic light-emitting layer 6 g and a CF 13g. The red organic EL element also has the same structure as the blueorganic EL element, except for an organic light-emitting layer 6 r and aCF 13 r. In this example, the substrate 1, the electron transport layer7, the transparent electrode 8, the thin-film passivation layer 9, theresin passivation layer 10, and the substrate 11 are shared by therespective organic EL elements of the R, G, and B colors, whereas otherlayers are partitioned by banks 12 among the respective organic ELelements of the R, G, and B colors.

Also, in the organic EL element of each of the R, G, and B colors, acavity structure is realized due to light interference phenomenon byproviding the corresponding reflective electrode 2. FIG. 2 shows anexample of a cavity structure in the blue organic EL element. Twooptical paths are formed in the blue organic EL element. One is a firstoptical path C1, in which a portion of light emitted from the organiclight-emitting layer 6 b travels through the first functional layertowards the reflective electrode 2, strikes and is reflected by thereflective electrode 2, and then is emitted externally after passingthrough the first functional layer, the organic light-emitting layer 6b, the second functional layer, and the transparent electrode 8. Theother is a second optical path C2, in which a remaining portion of thelight emitted from the organic light-emitting layer 6 b travels throughthe second functional layer towards the transparent electrode 8 insteadof towards the reflective electrode 2, and then is emitted externallyafter passing through the transparent electrode 8. By appropriatelysetting the film thickness of the first functional layer, it is possibleto cause light traveling the first optical path C1 and light travelingthe second optical path C2 to strengthen each other, thereby increasinglight-extraction efficiency.

In the present embodiment, the respective first functional layers of theR, G, and B colors have the same structure, and are formed from the samematerial. Also, the respective first functional layers of the R and Gcolors are equal in film thickness to each other, and differ in filmthickness from the first functional layer of the B color. Filmthicknesses adjustment for each of the R, G, and B colors is made on thehole transport layer 5. In other words, the respective hole transportlayers 5 of the R and G colors are equal in film thickness to eachother, and differ in film thickness from the hole transport layer 5 ofthe B color. Also, the respective transparent conductive layers 3 of theR, G, and B colors are equal in film thickness to one another, andrespective hole injection layers 4 of the R, G, and B colors are equalin film thickness to one another. The respective first functional layersof the R, G, and B colors have the same structure, and are formed fromthe same material. Accordingly, in terms of the optical distance fromthe reflective electrode of a corresponding color, the respectiveorganic light-emitting layers of the R and G colors are equal to eachother, and differ from the organic light-emitting layer of the B color.Note that for a single layer structure, the optical distance is theproduct of a film thickness and a refractive index, and for a multilayerstructure with two or more layers, the optical distance is the sum ofthe product of the film thickness and the refractive index for eachlayer.

Also, the respective second functional layers of the R, G, and B colorshave the same structure, are formed from the same material, and have thesame film thickness. Accordingly, the respective organic light-emittinglayers of the R, G, and B colors have the same optical distance from thetransparent electrode.

Also, the respective light-emitting layers of the R, G, and B colorsdiffer in material and film thickness. Specifically, the film thicknessof each of the respective organic light-emitting layers of the R, G, andB colors is adjusted so as to correspond to a local maximum oflight-extraction efficiency with respect to light after passing througha CF of a corresponding color.

Generally, the organic light-emitting layer needs to be formedseparately for each of the R, G, and B colors irrespective of whetherhaving the same film thickness among the R, G, and B colors, because ofbeing formed from a different material for each of the R, G, and Bcolors. Compared with this, the first functional layer and the secondfunctional layer are each formed from the same material among the R, G,and B colors. Accordingly, if differing in film thickness among the R,G, and B colors, the first functional layer and the second functionallayer each need to be formed separately for each of the R, G, and Bcolors. Otherwise, the first functional layer and the second functionallayer each do not need to be formed separately for each of the R, G, andB colors. In order to make a layer to differ in film thickness for eachof the R, G, and B colors, a printing method such as the inkjet methodfacilitates film formation for each of the R, G, and B colors. Notethat, depending on the type of layer, there is a case where the printingmethod is unavailable for film formation, a case where though theprinting method is available for film formation, other film formationmethod is more appropriate for exhibiting desired characteristics, orthe like. Accordingly, film formation cannot be always made by a filmformation method according to which film formation for each of the R, G,and B colors is easily made.

In the present embodiment, the respective organic light-emitting layers6 r, 6 g, and 6 b are formed so as to each have a different filmthickness. Also, the respective hole transport layers 5 of the R, G, andB colors are formed so as to each have a different film thickness. Inthis way, film formation is made separately to obtain a film thicknessfor each of the R, G, and B colors, and accordingly it is possible totake advantage of light interference phenomenon. Also, the respectiveorganic light-emitting layers 6 r, 6 g, and 6 b originally need to beseparately formed. Accordingly, there is no increase in the number ofmanufacturing processes due to formation of the organic light-emittinglayer to have a film thickness different for each of the R, G, and Bcolors. The hole transport layer 5 is appropriate for formation by theprinting method, and accordingly is easily formed separately to have afilm thickness for each of the R, G, and B colors. Also, the transparentconductive layer 3 and the hole injection layer 4 each have the samefilm thickness among the R, G, and B colors, and accordingly each do notneed to be formed separately to have a film thickness for each of the R,G, and B colors. As a result, it is possible to increaselight-extraction efficiency taking advantage of light interferencephenomenon, and simplify the manufacturing process compared withconventional arts.

The following describes in detail the film thickness of each layerconstituting an organic EL element.

[First Simulations]

The present inventors prepared Example 1 and Comparative example 1, andcalculated an optimal film thickness of each layer constituting anorganic EL element in Example 1 and Comparative example 1 throughsimulations to evaluate the light-extraction efficiency and thesimplicity of the manufacturing process.

In the first simulations, a reflective electrode is formed from an alloyof aluminum, a transparent conductive layer is formed from IZO (IndiumZinc Oxide), and respective organic light-emitting layers of the R, G,and B colors are formed from RP158, GP1200, and BP105 manufactured bySumation Co., Ltd., respectively. FIG. 3 shows the transmission spectrumof each of respective CFs of the R, G, and B colors used in the firstsimulations. The present inventors created the characteristics of theCFs (hereinafter, “CF characteristics”) used in the first simulations,by making appropriate adjustments based on a known art in view of theoptical characteristics in the present embodiment. For example, therespective CF characteristics for the R and G colors are based onJapanese Patent Application Publication 2005-116516 (FIG. 5), and the CFcharacteristics for the B color are based on B440 by Opto-Line, Inc.

FIG. 4A to FIG. 4D show variation of light-extraction efficiency whenvarying the film thickness of the first functional layer, FIG. 4A showsthe case where no CF is used in Example 1, FIG. 4B shows the case whereCFs are used in Example 1, FIG. 4C shows the case where no CF is used inComparative example 1, and FIG. 4D shows the case where CFs are used inComparative example 1.

In Example 1, an electron transport layer of each of the R, G, and Bcolors has a fixed film thickness of 30 nm, a hole injection layer ofeach of the R, G, and B colors has a fixed film thickness of 40 nm, atransparent conductive layer of each of the R, G, and B colors has afixed film thickness of 100 nm. Respective organic light-emitting layersof the R, G, and B colors have a fixed film thickness of 100 nm, a fixedfilm thickness of 80 nm, and a fixed film thickness of 30 nm,respectively. The film thickness of the first functional layer is variedby only variation of the film thickness of the hole transport layer.

In Comparative example 1, an electron transport layer of each of the R,G, and B colors has a fixed film thickness of 30 nm, a hole injectionlayer of each of the R, G, and B colors has a fixed film thickness of 40nm, a hole transport layer of each of the R, G, and B colors has a fixedfilm thickness of 20 nm. Respective organic light-emitting layers of theR, G, and B colors have a fixed film thickness of 80 nm, a fixed filmthickness of 80 nm, and a fixed film thickness of 60 nm, respectively.The film thickness of the first functional layer is varied by onlyvariation of the film thickness of the transparent conductive layer.

In the case where a CF is used, the following calculations are made withrespect to all the film thicknesses that are simulation targets tocalculate an optimal film thickness. An arbitrary film thickness isselected, and a chromaticity corresponding to the arbitrary filmthickness in the case where no CF is used is calculated. CFcharacteristics for approximating the calculated chromaticity to atarget chromaticity are calculated. Then, light-extraction efficiency inthe case where a CF having the calculated CF characteristics iscalculated.

FIG. 4A and FIG. 4C demonstrate the following points (1) and (2).

Point (1): Variation of the film thickness of the first functional layercauses cyclic variation of the light-extraction efficiency. As a result,a local maximum of light-extraction efficiency cyclically appears.

Point (2): When a local maximum that cyclically appears is referred toas the first local maximum, the second local maximum, and the thirdlocal maximum, . . . , in order of increasing film thickness of thefirst functional layer, a local maximum with a smaller degree has alarger value. With respect to the first functional layer of the B colorshown in FIG. 4A for example, while the second local maximum correspondsto a film thickness of around 40 nm, the third local maximum correspondsto a film thickness of around 180 nm. Accordingly, the second localmaximum has a larger value than the third local maximum. Note that whenthe hole transport layer has a film thickness of 0 nm, the firstfunctional layer has a film thickness of 140 nm. The first local maximumappears in a range of the film thickness of the first functional layerequal to or less than 140 nm, and accordingly does not appear in rangesshown in FIG. 4A.

The point (1) indicates that interference occurs between light travelingthe first optical path C1 and light traveling the second optical pathC2. Also, the point (2) indicates that the light-extraction efficiencyis increased more by setting the film thickness of the hole transportlayer so as to correspond to a local maximum with a smaller degree.

Also according to FIG. 4B, in order to increase the light-extractionefficiency in Example 1, it is optimal for the respective hole transportlayers of the R, G, and B colors to have a film thickness of 50 nm, afilm thickness of 50 nm, and a film thickness of 20 nm, respectively.According to FIG. 4D compared with Example 1, in order to increase thelight-extraction efficiency in Comparative example 1, it is optimal forthe respective transparent conductive layers of the R, G, and B colorsto have a film thickness of 140 nm, a film thickness of 120 nm, and afilm thickness of 90 nm, respectively. In this way, in terms of optimalfilm thickness for increasing the light-extraction efficiency, while therespective hole transport layers of the R and G colors are equal to eachother, and differ only from the hole transport layer of the B color inExample 1, the respective transparent conductive layers of the R, G, andB colors differ from one another in Comparative example 1. Thedifference between Example 1 and Comparative example 1 results from thefilm thickness adjustment on the organic light-emitting layer. Actually,in Example 1, the film thickness of the organic light emitting layer foreach of the R, G, and B colors is set such that the respective holetransport layers of the R, G, and B colors have, as much as possible,the same film thickness corresponding to the second local maximum oflight-extraction efficiency of a corresponding color in the case whereCFs are used. Specifically, the respective organic light-emitting layersof the R, G, and B colors have a film thickness of 100 nm, a filmthickness of 80 nm, and a film thickness of 30 nm, respectively. InComparative example 1 compared with Example 1, such a design concept wasnot introduced. The respective organic light-emitting layers of the R,G, and B colors are just set to have the same film thickness as much aspossible, within a scope that does not affect light emission.Specifically, the respective organic light-emitting layers of the R, G,and B colors have a film thickness of 80 nm, a film thickness of 80 nm,and a film thickness of 60 nm, respectively. Due to the difference indesign concept, there occurs a difference in results between Example 1and Comparative example 1.

As shown in FIG. 4A and FIG. 4C, the film thickness corresponding to alocal maximum sometimes differs between the case where no CF is used andthe case where CFs are used. Specifically, with respect to the B color,in the case where no CF is used, a film thickness of 40 nm of the firstfunctional layer corresponds to a local maximum of light-extractionefficiency. Compared with this, in the case where a CF is used, a filmthickness of 20 nm or less of the first functional layer corresponds toa local maximum of light-extraction efficiency. This suggests that inthe case where each layer constituting the first functional layer isdesigned so as to have an optimal film thickness on the assumptions thatno CF is used, the use of CFs does not necessarily make each designedlayer to have an optimal film thickness. In other words, in the casewhere the use of CFs is assumed, the film thickness of each layer needsto be considered in view of the CF characteristics. In Example 1, theresults are obtained after consideration of the film thickness of eachlayer in view of the CF characteristics, and an optimal design is madefor the case where CFs are used.

In Example 1, the respective hole transport layers of the R and G colorsare equal in film thickness to each other, and differ in film thicknessonly from the hole transport layer of the B color. Also, the respectiveorganic light-emitting layers of the R, G, and B colors differ in filmthickness to one another. As shown below, it is often the case where thelight-extraction efficiency is increased more by making film thicknessadjustment on the organic light-emitting layer for each of the R, G, andB colors than by making film thickness adjustment on the hole transportlayer.

FIG. 5A to FIG. 5D each show variation of light-extraction efficiencywhen varying the film thickness of a layer constituting an EL element.Specifically, FIG. 5A and FIG. 5B show variation of light-extractionefficiency when varying the film thickness of the hole transport layer,in the case where no CF is used and the case where CFs are used,respectively. FIG. 5C and FIG. 5D show variation of light-extractionefficiency when varying the film thickness of the organic light-emittinglayer, in the case where no CF is used and the case where CFs are used,respectively.

Comparison of FIG. 5B and FIG. 5D shows that the hole transport layerand the organic light-emitting layer are substantially equal in cycle ofvariation of light-extraction efficiency corresponding to the filmthickness, and differ in variation width of the light-extractionefficiency, specifically, have a variation width h1 and a variationwidth h2, respectively. In other words, the organic light-emitting layeris smaller in ratio of variation of light-extraction efficiency tovariation of film thickness than the hole transport layer.

In the case where the inkjet method is used for forming each layerconstituting the organic EL element, the film thickness of the layer isadjusted by adjusting the number of drops of ink. Since the amount ofone drop of ink is the minimum unit for adjustment of film thickness,the film thickness adjustment needs to be made not continuously butdiscretely. In this case, film thickness adjustment should be made on alayer having a smaller ratio of variation of light-extraction efficiencyto variation of film thickness. This is advantageous for exactadjustment on the layer so as to have a film thickness corresponding tothe highest light-extraction efficiency.

In Example 1, film thickness adjustment for each of the R, G, and Bcolors is mainly made on the organic light-emitting layer. This makes iteasy to exactly adjust the layer so as to have a film thicknesscorresponding to the highest light-extraction efficiency.

FIG. 6A and FIG. 6B show light-extraction efficiency and so on when eachlayer constituting an organic EL element is set to have an optimal filmthickness in Example 1 and Comparative example 1, respectively.

In Example 1 as described above, the respective hole transport layers ofthe R, G, and B colors have an optimal film thickness of 50 nm, anoptimal film thickness of 50 nm, and an optimal film thickness of 20 nm,respectively. Also, respective organic light-emitting layers of the R,G, and B colors have an optimal film thickness of 100 nm, an optimalfilm thickness of 80 nm, and an optimal film thickness of 30 nm,respectively. Here, the respective organic EL elements of the R, G, andB colors exhibit a light-extraction efficiency of 1.8 cd/A, alight-extraction efficiency of 4.6 cd/A, and a light-extractionefficiency of 0.40 cd/A, respectively. Also, the respective organic ELelements of the R, G, and B colors exhibit a chromaticity of(0.66,0.34), a chromaticity of (0.28,0.68), and a chromaticity(0.13,0.06), respectively. Furthermore, respective tolerable limits ofdifference in film thickness of the first functional layers of the R, G,and B colors are a range of −10 nm to +10 nm, a range of −10 nm to +10nm, and a range of −15 nm to +9 nm, respectively. Tolerable marginwidths of the first functional layers of the R, G, and B colors are 20nm, 20 nm, and 24 nm, respectively.

The “tolerable limits of difference in film thickness” indicate thetolerable limits of difference in film thickness of each layer from theoptimal value under the conditions that allowable ranges shown in FIG. 7are satisfied. FIG. 7 shows the following allowable ranges of:

(1) 20% or lower variation of light-extraction efficiency at a surfaceof the organic EL panel;

(2) variation of chromaticity of x of 0.04 or less and y of 0.04 or lessat the surface of the organic EL panel;

(3) a brightness of 90% or higher at a viewing angle of 30° with respectto a brightness at a viewing angle of 0° and a brightness of 80% orhigher at a viewing angle of 45° with respect to a brightness at aviewing angle of 0°; and

(4) difference in chromaticity of x of 0.04 or less and y of 0.04 orless between a viewing angle of 50° and a viewing angle of 0°.

Broader tolerable limits of difference in film thickness make it easierto adjust the film thickness on each layer during the manufacturingprocess. The “tolerable margin width” indicates a difference between theupper limit and the lower limit in the tolerable limits of difference infilm thickness (for example, each layer of the R color in Example 1 hasa tolerable margin width of 20 which is the difference between the upperlimit of +10 and the lower limit of −10).

In Comparative example 1 compared with Example 1, the respectivetransparent conductive layers of the R, G, and B colors have an optimalfilm thickness of 140 nm, an optimal film thickness of 120 nm, and anoptimal film thickness of 90 nm, respectively. Here, the respectiveorganic EL elements of the R, G, and B colors exhibit a light-extractionefficiency of 1.8 cd/A, a light-extraction efficiency of 4.4 cd/A, and alight-extraction efficiency of 0.40 cd/A, respectively. Also, therespective organic EL elements of the R, G, and B colors exhibit achromaticity of (0.66,0.34), a chromaticity of (0.28,0.68), and achromaticity (0.13,0.06), respectively. Furthermore, respectivetolerable limits of difference in film thickness of the first functionallayers of the R, G, and B colors are a range of −10 nm to +10 nm, arange of −6 nm to +15 nm, and a range of −15 nm to +9 nm, respectively.Tolerable margin widths of the first functional layers of the R, G, andB colors are 20 nm, 21 nm, and 24 nm, respectively.

According to Example 1 as described above, film thickness adjustment ismade on the organic light-emitting layer, which originally needs to beformed separately for each of the R, G, and B colors, and also filmthickness adjustment is made on the hole transport layer, which iseasily formed by the printing method typified by the inkjet method. Thisexhibits the light-extraction efficiency and the chromaticity that areat the same level as those exhibited in Comparative example 1. As aresult, it is possible to realize both the increase in light-extractionefficiency and the simplification of the manufacturing process.

Also in more detail, each layer constituting the organic EL elementshould have a film thickness within a range of ±10% of a film thicknessobtained through the simulations in view of manufacturing errors. FIG.8A to FIG. 8C each show the minimum value, the average value, and themaximum value of the film thickness of each layer constituting theorganic EL element in Example 1, with respect to the R, G, and B colors,respectively. Specifically, the respective transparent conductive layersof the R, G, and B colors each should have a film thickness of 90 nm to110 nm. The respective hole injection layers of the R, G, and B colorseach should have a film thickness of 36 nm to 44 nm. The respectiveelectron transport layers of the R, G, and B colors each should have afilm thickness of 27 nm to 33 nm. Here, the respective organiclight-emitting layers of the R and G colors each have an opticaldistance of 331 nm to 404 nm from the reflective electrode of acorresponding color, and the organic light-emitting layer of the B colorhas an optical distance of 285 nm to 348 nm from the reflectiveelectrode of a corresponding color. The respective organiclight-emitting layers of the R, G, and B colors each have an opticaldistance of 48.6 nm to 59.4 nm from the transparent electrode. Also, therespective hole transport layers of the R and G colors should have afilm thickness of 45 nm to 55 nm, the hole transport layer of the Bcolor should have a film thickness of 18 nm to 22 nm. The respectiveorganic light-emitting layers of the R, G, and B colors should have afilm thickness of 90 nm to 110 nm, a film thickness of 72 nm to 88 nm,and a film thickness of 27 nm to 33 nm, respectively.

[Specific Examples of Each Layer]

<Substrate>

The substrate 1 is a Thin Film Transistor (TFT) substrate, for example.The substrate 1 is a glass plate or quartz plate of soda glass,nonfluorescent glass, phosphate glass, borate glass, or the like; aplastic plate or plastic film of acrylic resin, styrenic resin,polycarbonate resin, epoxy resin, polyethylene, polyester, siliconeresin, or the like; or a metal plate or metal foil of alumina or thelike.

<Banks>

The banks 12 should be formed from an insulating material, and it ispreferable that the banks 12 have organic solvent resistance.Furthermore, since the banks 12 undergo etching, baking, and the like,it is preferable that the banks 12 be formed from a material that ishighly resistant to such processes. The material for the banks 12 may bean organic material such as resin, or an inorganic material such asglass. As an organic material, acrylic resin, polyimide resin,novolac-type phenolic resin, and the like can be used. As an inorganicmaterial, silicon dioxide (SiO₂), silicon nitride (Si₃N₄), and the likecan be used.

<Reflective Electrode>

The reflective electrode 2 is electrically connected to the TFT providedon the substrate 1. In addition to functioning as a positive terminal ofthe organic EL element, the reflective electrode 2 has the function ofreflecting light emitted from the organic light-emitting layers 6 b, 6g, and 6 r towards the reflective electrode 2. The reflecting functionmay be achieved by the structural material of the reflective electrode 2or by applying a reflective coating to the surface portion of thereflective electrode 2. For example, the reflective electrode 2 isformed from Ag (silver), APC (alloy of silver, palladium, and copper),ARA (alloy of silver, rubidium, and gold), MoCr (alloy of molybdenum andchromium), NiCr (alloy of nickel and chromium), or the like.

<Transparent Conductive Layer>

The transparent conductive layer 3 functions as a protective layer toprevent the reflective electrode 2 from naturally oxidizing during themanufacturing process. The material for the transparent conductive layer3 should be formed from a conductive material sufficiently translucentwith respect to light emitted by the organic light-emitting layers 6 b,6 g, and 6 r. For example, the transparent conductive layer 3 ispreferably formed from ITO or IZO, which achieve good conductivity evenwhen a film thereof is formed at room temperature.

<Hole Injection Layer>

The hole injection layer 4 has the function of injecting holes into theorganic light-emitting layers 6 b, 6 g, and 6 r. The hole injectionlayer 4 is formed from an oxide of a transition metal, such as tungstenoxide (WOx), molybdenum oxide (MoOx), and molybdenum tungsten oxide(MoxWyOz). Forming the hole injection layer 4 from an oxide of atransition metal allows for improvement of voltage-current densitycharacteristics, and for an increase in emission intensity by increasingcurrent density. Note that other metal compounds, such as a transitionmetal nitride, may also be used.

<Hole Transport Layer>

Examples of the material for the hole transport layer 5 include atriazole derivative, an oxadiazole derivative, an imidazole derivative,a polyarylalkane derivative, a pyrazoline derivative and pyrazolonederivative, a phenylenediamine derivative, an arylamine derivative, anamino-substituted chalcone derivative, an oxazole derivative, astyrylanthracene derivative, a fluorenone derivative, a hydrazonederivative, a stilbene derivative, a porphyrin compound, an aromatictertiary amine compound and styrylamine compound, a butadiene compound,a polystyrene derivative, a hydrazone derivative, a triphenylmethanederivative, or a tetraphenylbenzene derivative, as disclosed in JapanesePatent Application Publication No. 5-163488. In particular, a porphyrincompound, as well as an aromatic tertiary amine compound and styrylaminecompound, are preferable.

<Organic Light-Emitting Layer>

The organic light-emitting layers 6 b, 6 g, and 6 r are formed from afluorescent material such as, for example, an oxinoid compound, perylenecompound, coumarin compound, azacoumarin compound, oxazole compound,oxadiazole compound, perinone compound, pyrrolo-pyrrole compound,naphthalene compound, anthracene compound, fluorene compound,fluoranthene compound, tetracene compound, pyrene compound, coronenecompound, quinolone compound and azaquinolone compound, pyrazolinederivative and pyrazolone derivative, rhodamine compound, chrysenecompound, phenanthrene compound, cyclopentadiene compound, stilbenecompound, diphenylquinone compound, styryl compound, butadiene compound,dicyanomethylene pyran compound, dicyanomethylene thiopyran compound,fluorescein compound, pyrylium compound, thiapyrylium compound,selenapyrylium compound, telluropyrylium compound, aromatic aldadienecompound, oligophenylene compound, thioxanthene compound, anthracenecompound, cyanine compound, acridine compound, metal complex of a8-hydroxyquinoline compound, metal complex of a 2-bipyridine compound,complex of a Schiff base and a group three metal, metal complex ofoxine, rare earth metal complex, and the like, as recited in JapanesePatent Application Publication No. H5-163488.

<Electron Transport Layer>

Examples of the material for the electron transport layer 7 include anitro-substituted fluorenone derivative, a thiopyran dioxide derivative,a diphenylquinone derivative, a perylene tetracarboxyl derivative, ananthraquinodimethane derivative, a fluoronylidene methane derivative, ananthrone derivative, an oxadiazole derivative, a perinone derivative,and a quinolone complex derivative, as recited in Japanese PatentApplication Publication No. H5-163488.

Note that from the perspective of further improving electron injectioncharacteristics, the above materials for forming the electron transportlayer may be doped with an alkali metal or an alkaline-earth metal, suchas Na, Ba, or Ca.

<Transparent Electrode>

The transparent electrode 8 functions as a negative electrode for theorganic EL element. The material for the transparent electrode 8 shouldbe formed from a conductive material sufficiently translucent withrespect to light emitted by the organic light-emitting layers 6 b, 6 g,and 6 r. For example, the transparent electrode 8 is preferably formedfrom ITO or IZO.

<Thin-Film Passivation Layer>

The thin-film passivation layer 9 has the function of preventing thelayers interposed between the substrate 1 and the thin-film passivationlayer 9 from being exposed to moisture or air. The material for thethin-film passivation layer 9 is, for example, silicon nitride (SiN),silicon oxynitride (SiON), resin, or the like.

<Resin Passivation Layer>

The resin passivation layer 10 has the functions of adhering a backpanel, which is composed of the layers from the substrate 1 to thethin-film passivation layer 9, to the substrate 11, on which are formedthe color filters 13 b, 13 g, and 13 r, and of preventing the layersfrom being exposed to moisture or air. The material for the resinpassivation layer 10 is, for example, a resin adhesive or the like.

<Color Filters>

The color filters 13 b, 13 g, and 13 r have the function of correctingthe chromaticity of light emitted by the organic light-emitting layers.

[Organic Display Device]

FIG. 9 is a functional block showing an organic display device accordingto the embodiment of the present invention. FIG. 10 is an exemplaryexternal diagram showing the organic display device according to theembodiment of the present invention. An organic display device 15includes an organic display panel 16 and a drive control unit 17 thatare electrically connected to each other. The organic display panel 16has the pixel structure shown in FIG. 1. The drive control unit 17includes drive circuits 18 to 21 that apply voltage between thereflective electrode 2 corresponding to each organic EL element and atransparent electrode 8, and a control circuit 22 that controlsoperations of the drive circuits 18 to 21.

[Method of Manufacturing Organic EL Panel]

Next, the method of manufacturing an organic EL panel is described. FIG.11A to FIG. 11D and FIG. 12A to FIG. 12C show a method of manufacturingan organic EL panel according to the embodiment of the presentinvention.

First, reflective electrodes 2 are formed on a substrate 1 by a vapordeposition method, a sputtering method, or the like (FIG. 11A). Next,transparent conductive layers 3 are formed on the respective reflectiveelectrodes 2 by the vapor deposition method, the sputtering method, orthe like (FIG. 11B). The respective transparent conductive layers 3 ofthe R, G, and B colors are set to have the same film thickness.

Next, on each of the transparent conductive layers 3, a hole injectionlayer 4, for example, is formed by a physical vapor deposition methodsuch as the vapor deposition method and the sputtering method. Then,banks 12 are formed. Furthermore, on each of the hole injection layers4, a hole transport layer 5, for example, is formed by a printing methodsuch as the inkjet method (FIG. 11C). The respective hole injectionlayers 4 of the R, G, and B colors are set to have the same filmthickness. Also, the respective hole transport layers 5 of the R and Gcolors are set to have the same film thickness, and to have a differentfilm thickness from the hole transport layer 5 of the B color.

Next, on the respective hole transport layers 5, light-emitting layers 6b, 6 g, and 6 r, for example, are formed by a printing method such asthe inkjet method (FIG. 11D). The respective organic light-emittinglayers 6 b, 6 g, and 6 r are set to appropriately have a different filmthickness.

Next, on the light-emitting layers 6 b, 6 g, and 6 r, an electrontransport layer 7 is formed by the vapor deposition method, thesputtering method, or the like (FIG. 12A). The respective electrontransport layers 7 of the R, G, and B colors are set to have the samefilm thickness.

Next, on the electron transport layer 7, a transparent electrode 8 isformed by the vapor deposition method, the sputtering method, or thelike (FIG. 12B). The transparent electrode 8 has a film thickness of 90nm to 110 nm, for example.

Next, a thin-film passivation layer 9 is formed on the transparentelectrode 8 by the vapor deposition method, the sputtering method, orthe like, and a substrate 11 in which color filters 13 b, 13 g, and 13 rare formed is adhered thereto using a resin passivation layer 10 (FIG.12C). These passivation layers each have a film thickness of 900 nm to1100 nm, for example.

Although the present invention has been described based on the aboveembodiment, the present invention is not limited to the aboveembodiment. The present invention may include the following modificationexamples.

(1) In Example 1, the respective first functional layers of the R and Gcolors each have a film thickness of 171 nm to 209 nm, and the firstfunctional layer of the B color has a film thickness of 144 nm to 176nm. The present invention is not limited to this. It is considered thatthe effect of increasing the light-extraction efficiency is exhibiteddue to the interference phenomenon that occurs between light travelingthe first optical path C1 and light traveling the second optical pathC2. This leads to an idea that what is important is not the filmthickness of the first functional layer, but the optical distancebetween the organic light-emitting layer and the reflective electrode.Therefore, the respective organic light-emitting layers of the R and Gcolors each should have an optical distance of 331 nm to 404 nm from thereflective electrode of a corresponding color, and the organiclight-emitting layer of the B color should have an optical distance of285 nm to 348 nm from the reflective electrode. As long as thiscondition is satisfied, the same effect is exhibited even if the filmthickness of the first functional layer is varied.

Also, although the second functional layer has a film thickness of 27min to 33 nm, the present invention is not limited to this similarly.The respective organic light-emitting layers of the R, G, and B colorseach should have an optical distance of 48.6 nm to 59.4 nm. As long asthis condition is satisfied, the same effect is exhibited even if thefilm thickness of the second functional layer is varied.

(2) In the above embodiment, the first functional layer is constitutedfrom the transparent conductive layer, the hole injection layer, and thehole transport layer. Alternatively, the first functional layer may notinclude any one of the transparent conductive layer, the hole injectionlayer, and the hole transport layer. Further alternatively, the firstfunctional layer may further include another functional layer.

(3) In the above embodiment, the second functional layer is constitutedfrom the hole transport layer. Alternatively, the second functionallayer may further include an electron injection layer, for example.

INDUSTRIAL APPLICABILITY

The present invention is applicable to organic EL displays and the like.

REFERENCE SIGNS LIST

-   -   1 substrate    -   2 reflective electrode    -   3 transparent conductive layer    -   4 hole injection layer    -   5 hole transport layer    -   6 b, 6 g, and 6 r organic light-emitting layer    -   7 electron transport layer    -   8 transparent electrode    -   9 thin-film passivation layer    -   resin passivation layer    -   11 substrate    -   12 bank    -   13 b, 13 g, and 13 r color filter    -   15 organic display device    -   16 organic display panel    -   17 drive control unit    -   18 to 21 drive circuit    -   22 control circuit

The invention claimed is:
 1. An organic electro luminescence (EL) panel,comprising: a first electrode of each of red (R), green (G), and blue(B) colors that reflects incident light; a second electrode that facesthe first electrode of each of the R, G, and B colors, and transmitsincident light therethrough; an organic light-emitting layer of each ofthe R, G, and B colors that is disposed between the first electrode of acorresponding color and the second electrode, and emits light of acorresponding color due to voltage application between the firstelectrode of the corresponding color and the second electrode; a firstfunctional layer of each of the R, G, and B colors that includes acharge injection/transport layer and at least one other layer, and isdisposed between the first electrode of a corresponding color and theorganic light-emitting layer of a corresponding color; a secondfunctional layer of each of the R, G, and B colors that is disposedbetween the second electrode and the organic light-emitting layer of acorresponding color; and a color filter of each of the R, G, and Bcolors for chromaticity correction that is disposed opposite the organiclight-emitting layer of a corresponding color with the second electrodebeing interposed therebetween, wherein a first portion of light of eachof the R, G, and B colors emitted from the organic light-emitting layerof a corresponding color travels through the first functional layer of acorresponding color towards the first electrode of a correspondingcolor, strikes and is reflected by the first electrode of thecorresponding color, and then is emitted externally after passingthrough the first functional layer of the corresponding color, theorganic light-emitting layer of the corresponding color, the secondfunctional layer of a corresponding color, the second electrode, and thecolor filter of a corresponding color, a second portion of the light ofeach of the R, G, and B colors travels through the second functionallayer of the corresponding color towards the second electrode instead oftowards the first electrode of the corresponding color, and is emittedexternally after passing through the second electrode and the colorfilter of the corresponding color, the respective chargeinjection/transport layers of the R, G, and B colors each include acharge injection layer and a charge transport layer, the respectivecharge injection layers of the R, G, and B colors are equal in filmthickness to each other, the respective charge transport layers of the Rand G colors are equal in film thickness to each other, and differ infilm thickness from the charge transport layer of the B color, therespective charge injection layers of the R, G, and B colors are eachpositioned on a corresponding one of the respective other layers of theR, G, and B colors, the respective charge transport layers of the R, G,and B colors are each positioned on a corresponding one of therespective charge injection layers of the R, G, and B colors, therespective at least one other layers of the R, G, and B colors are equalin film thickness to one another, the respective second functionallayers of the R, G, and B colors are equal in film thickness to oneanother, and the respective organic light-emitting layers of the R, G,and B colors differ in film thickness from one another.
 2. The organicEL panel of claim 1, wherein the film thickness of the organiclight-emitting layer of each of the R, G, and B colors is adjusted so asto correspond to a local maximum of light-extraction efficiency withrespect to the light of the corresponding color emitted externallythrough the color filter of the corresponding color.
 3. The organic ELpanel of claim 2, wherein a film thickness of the first functional layerof each of the R, G, and B colors is adjusted so as to correspond to asecond local maximum of the light-extraction efficiency with respect tothe light of the corresponding color emitted externally through thecolor filter of the corresponding color.
 4. The organic EL panel ofclaim 1, wherein the first functional layer of each of the R, G, and Bcolors includes, as the at least one other layer, a transparentconductive layer.
 5. The organic EL panel of claim 1, wherein the firstfunctional layer of each of the R, G, and B colors includes a layerformed by a printing method and a layer formed by a physical vapordeposition method, the respective layers of the R and G colors formed bythe printing method are equal in film thickness to each other, anddiffer in film thickness from the layer of the B color formed by theprinting method, and the respective layers of the R, G, and B colorsformed by the physical vapor deposition method are equal in filmthickness to one another.
 6. The organic EL panel of claim 1, whereinthe respective organic light-emitting layers of the R, G, and B colorshave a film thickness of 90 nm to 110 nm, a film thickness of 72 nm to88 nm, and a film thickness of 27 nm to 33 nm, respectively, the firstfunctional layer of each of the R, G, and B colors includes, as the atleast one other layer, a transparent conductive layer formed on an anodethat is the first electrode of the corresponding color, the firstfunctional layer of each of the R, G, and B colors includes, as thecharge injection/transport layer, a hole injection layer formed on thetransparent conductive layer and a hole transport layer formed on thehole injection layer, the respective transparent conductive layers ofthe R, G, and B colors each have a film thickness of 90 nm to 110 nm,the respective hole injection layers of the R, G, and B colors each havea film thickness of 36 nm to 44 nm, and the respective hole transportlayers of the R and G colors each have a film thickness of 45 nm to 55nm, and the hole transport layer of the B color has a film thickness of18 nm to 22 nm.
 7. The organic EL panel of claim 6, wherein the firstelectrode of each of the R, G, and B colors is formed from aluminum oralloy of aluminum, and the transparent conductive layer of each of theR, G, and B colors is formed from Indium Zinc Oxide.
 8. The organic ELpanel of claim 7, wherein the respective second functional layers of theR, G, and B colors each have a film thickness of 27 nm to 33 nm.
 9. Theorganic EL panel of claim 8, wherein the second functional layer of eachof the R, G, and B colors includes an electron transport layer having afilm thickness of 27 nm to 33 nm.
 10. The organic EL panel of claim 1,wherein the organic light-emitting layer of each of the R, G, and Bcolors contains an organic material, and is formed by a printing method.11. The organic EL panel of claim 1, wherein the first functional layerof each of the R, G, and B colors includes, as the at least one otherlayer, a transparent conductive layer formed on an anode that is thefirst electrode of the corresponding color, the first functional layerof each of the R, G, and B colors includes, as the chargeinjection/transport layer, a hole injection layer formed on thetransparent conductive layer and a hole transport layer formed on thehole injection layer, the transparent conductive layer of each of the R,G, and B colors and the hole injection layer of each of the R, G, and Bcolors are formed by a physical vapor deposition method, and the holetransport layer of each of the R, G, and B colors is formed by aprinting method.
 12. A display device with use of the organic EL panelof claim
 1. 13. A method of manufacturing an organic electroluminescence (EL) panel, comprising: a preparing a first electrode ofeach of red (R), green (G), and blue (B) colors that reflects incidentlight; a of disposing a first functional layer of each of the R, G, andB colors including a charge injection/transport layer and at least oneother layer on the first electrode of a corresponding color; disposingan organic light-emitting layer that emits light of each of the R, G,and B colors on the first functional layer of a corresponding color;disposing a second functional layer of each of the R, G, and B colors onthe organic light-emitting layer of a corresponding color; disposing asecond electrode that transmits incident light therethrough on therespective second functional layers of the R, G, and B colors so as toface the respective first electrodes of the R, G, and B colors; anddisposing a color filter of each of the R, G, and B colors forchromaticity correction so as to be opposite the organic light-emittinglayer of a corresponding color with the second electrode beinginterposed therebetween, wherein the respective chargeinjection/transport layers of the R, G, and B colors each include acharge injection layer and a charge transport layer, the respectivecharge injection layers of the R, G, and B colors are equal in filmthickness to each other, the respective charge transport layers of the Rand G colors are equal in film thickness to each other, and differ infilm thickness from the charge transport layer of the B color, therespective charge injection layers of the R, G, and B colors are eachpositioned on a corresponding one of the respective other layers of theR, G, and B colors, the respective charge transport layers of the R, G,and B colors are each positioned on a corresponding one of therespective charge injection layers of the R, G, and B colors, therespective at least one other layers of the R, G, and B colors are equalin film thickness to one another, the respective organic light-emittinglayers of the R, G, and B colors differ in film thickness from oneanother, and the respective second functional layers of the R, G, and Bcolors are equal in film thickness to one another.
 14. An organicelectro luminescence (EL) panel, comprising: a first electrode of eachof red (R), green (G), and blue (B) colors that reflects incident light;a second electrode that faces the first electrode of each of the R, G,and B colors, and transmits incident light therethrough; an organiclight-emitting layer of each of the R, G, and B colors that is disposedbetween the first electrode of a corresponding color and the secondelectrode, and emits light of a corresponding color due to voltageapplication between the first electrode of the corresponding color andthe second electrode; a first functional layer of each of the R, G, andB colors that includes a charge injection/transport layer and at leastone other layer, and is disposed between the first electrode of acorresponding color and the organic light-emitting layer of acorresponding color; a second functional layer of each of the R, G, andB colors that is disposed between the second electrode and the organiclight-emitting layer of a corresponding color; and a color filter ofeach of the R, G, and B colors for chromaticity correction that isdisposed opposite the organic light-emitting layer of a correspondingcolor with the second electrode being interposed therebetween, wherein afirst portion of light of each of the R, G, and B colors emitted fromthe organic light-emitting layer of a corresponding color travelsthrough the first functional layer of a corresponding color towards thefirst electrode of a corresponding color, strikes and is reflected bythe first electrode of the corresponding color, and then is emittedexternally after passing through the first functional layer of thecorresponding color, the organic light-emitting layer of thecorresponding color, the second functional layer of a correspondingcolor, the second electrode, and the color filter of a correspondingcolor, a second portion of the light of each of the R, G, and B colorstravels through the second functional layer of the corresponding colortowards the second electrode instead of towards the first electrode ofthe corresponding color, and is emitted externally after passing throughthe second electrode and the color filter of the corresponding color,the respective charge injection/transport layers of the R and G colorsare equal in film thickness to each other, and differ in film thicknessfrom the charge injection/transport layer of the B color, the respectiveat least one other layers of the R, G, and B colors are equal in filmthickness to one another, the respective second functional layers of theR, G, and B colors are equal in film thickness to one another, therespective organic light-emitting layers of the R, G, and B colorsdiffer in film thickness from one another, and the film thickness of theorganic light-emitting layer of each of the R, G, and B colors isadjusted so as to correspond to a local maximum of light-extractionefficiency with respect to the light of the corresponding color emittedexternally through the color filter of the corresponding color.
 15. Anorganic electro luminescence (EL) panel, comprising: a first electrodeof each of red (R), green (G), and blue (B) colors that reflectsincident light; a second electrode that faces the first electrode ofeach of the R, G, and B colors, and transmits incident lighttherethrough; an organic light-emitting layer of each of the R, G, and Bcolors that is disposed between the first electrode of a correspondingcolor and the second electrode, and emits light of a corresponding colordue to voltage application between the first electrode of thecorresponding color and the second electrode; a first functional layerof each of the R, G, and B colors that includes a chargeinjection/transport layer and at least one other layer, and is disposedbetween the first electrode of a corresponding color and the organiclight-emitting layer of a corresponding color; a second functional layerof each of the R, G, and B colors that is disposed between the secondelectrode and the organic light-emitting layer of a corresponding color;and a color filter of each of the R, G, and B colors for chromaticitycorrection that is disposed opposite the organic light-emitting layer ofa corresponding color with the second electrode being interposedtherebetween, wherein a first portion of light of each of the R, G, andB colors emitted from the organic light-emitting layer of acorresponding color travels through the first functional layer of acorresponding color towards the first electrode of a correspondingcolor, strikes and is reflected by the first electrode of thecorresponding color, and then is emitted externally after passingthrough the first functional layer of the corresponding color, theorganic light-emitting layer of the corresponding color, the secondfunctional layer of a corresponding color, the second electrode, and thecolor filter of a corresponding color, a second portion of the light ofeach of the R, G, and B colors travels through the second functionallayer of the corresponding color towards the second electrode instead oftowards the first electrode of the corresponding color, and is emittedexternally after passing through the second electrode and the colorfilter of the corresponding color, the respective chargeinjection/transport layers of the R and G colors are equal in filmthickness to each other, and differ in film thickness from the chargeinjection/transport layer of the B color, the respective at least oneother layers of the R, G, and B colors are equal in film thickness toone another, the respective second functional layers of the R, G, and Bcolors are equal in film thickness to one another, the respectiveorganic light-emitting layers of the R, G, and B colors differ in filmthickness from one another, and a film thickness of the first functionallayer of each of the R, G, and B colors is adjusted so as to correspondto a second local maximum of the light-extraction efficiency withrespect to the light of the corresponding color emitted externallythrough the color filter of the corresponding color.